System and method for determining a position for a scleral pocket for a scleral prosthesis

ABSTRACT

For use with a surgical tool for making incisions in the sclera of an eye to form a scleral pocket to receive a scleral prosthesis, a system and method is disclosed for determining a position on the sclera for locating the scleral pocket. The system and method determines an optimum location for the scleral pocket. The system and method determines a location on the sclera that represents the intersection of the lens equatorial plane with the external surface of the sclera. The front of the scleral pocket is placed at a location that is four hundred fifty microns posterior to the intersection of the lens equatorial plane with the external surface of the sclera.

PRIORITY CLAIM TO PRIOR PATENT APPLICATIONS

This patent application claims priority to U.S. Provisional PatentApplication Ser. No. 60/381,851 filed on May 20, 2002. This patentapplicant claims priority as a continuation-in-part patent applicationto U.S. patent application Ser. No. 10/080,877 filed on Feb. 22, 2002and to U.S. patent application Ser. No. 10/080,986 filed on Feb. 22,2002.

CROSS-REFERENCE TO RELATED PATENT DOCUMENTS

The present disclosure is related to the inventions disclosed in thefollowing United States patent applications and issued United Statespatents:

-   -   (1) U.S. Pat. No. 6,299,640 entitled “SCLEPAL P ROSTHESIS FOR        TREATMENT OF PRESBYOPIA AND OTHER EYE DISORDERS” issued on Oct.        9, 2001;    -   (2) U.S. Pat. No. 6,197,056 entitled “SEGMENTED SCLERAL BAND FOR        TREATMENT OF PRESBYOPIA AND OTHER EYE DISORDERS” issued on Mar.        6, 2001;    -   (3) U.S. Pat. No. 6,280,468 entitled “SCLERAL PROSTHESIS FOR        TREATMENT OF PRESBYOPIA AND OTHER EYE DISORDERS” issued Aug. 28,        2001;    -   (4) U.S. Pat. No. 5,465,737 entitled “TREATMENT OF PRESBYOPIA        AND OTHER EYE DISORDERS” issued on Nov. 14, 1995;    -   (5) U.S. Pat. No. 5,489,299 entitled “TREATMENT OF PRESBYOPIA        AND OTHER EYE DISORDERS” issued on Feb. 6, 1996;    -   (6) U.S. Pat. No. 5,503,165 entitled “TREATMENT OF PRESBYOPIA        AND OTHER EYE DISORDERS” issued on Apr. 2, 1996;    -   (7) U.S. Pat. No. 5,529,076 entitled “TREATMENT OF PRESBYOPIA        AND OTHER EYE DISORDERS” issued on Jun. 25, 1996;    -   (8) U.S. Pat. No. 5,354,331 entitled “TREATMENT OF PRESBYOPIA        AND OTHER EYE DISORDERS” issued on Oct. 11, 1994; and    -   (9) U.S. Pat. No. 5,722,952 entitled “TREATMENT OF PRESBYOPIA        AND OTHER EYE DISORDERS” issued on Mar. 3, 1998;    -   (10) U.S. patent application Ser. No. 10/080,877 entitled        “SYSTEM AND METHOD FOR MAKING INCISIONS FOR SCLERAL EYE        IMPLANTS” filed on Feb. 22, 2002; and    -   (11) U.S. patent application Ser. No. 10/080,986 entitled        “SURGICAL BLADE FOR USE WITH A SURGICAL TOOL FOR MAKING        INCISIONS FOR SCLERAL EYE IMPLANTS” filed on Feb. 22, 2002 which        are commonly owned by the assignee of the present invention. The        disclosures of these related United States patent applications        and issued United States patents (collectively referred to        hereafter as the “Presbyopia and Related Eye Disorder Patent        Documents”) are incorporated herein by reference for all        purposes as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates generally to the treatment of presbyopia,hyperopia, primary open angle glaucoma, ocular hypertension and othersimilar eye disorders. The present invention comprises a system andmethod for determining a position for making an incision in the scleraof an eye to form a scleral pocket for the eye to receive a scleralprosthesis. Scleral prostheses are capable of increasing the amplitudeof accommodation of the eye by increasing the effective working distanceor range of the ciliary muscle of the eye.

BACKGROUND OF THE INVENTION

In order for the human eye to have clear vision of objects at differentdistances, the effective focal length of the eye must be adjusted tokeep the image of the object focused as sharply as possible on theretina. This change in effective focal length is known as accommodationand is accomplished in the eye by varying the shape of the crystallinelens. Generally, in the unaccommodated emmetropic eye the curvature ofthe lens is such that distant objects are sharply imaged on the retina.In the unaccommodated eye near objects are not focused sharply on theretina because their images lie behind the retinal surface. In order tovisualize a near object clearly, the curvature of the crystalline lensis increased, thereby increasing its refractive power and causing theimage of the near object to fall on the retina.

The change in shape of the crystalline lens is accomplished by theaction of certain muscles and structures within the eyeball or globe ofthe eye. The lens is located in the forward part of the eye, immediatelybehind the pupil. It has the shape of a classical biconvex optical lens,i.e., it has a generally circular cross section having two convexrefracting surfaces, and is located generally on the optical axis of theeye, i.e., a straight line drawn from the center of the cornea to themacula in the retina at the posterior portion of the globe. In theunaccommodated human eye the curvature of the posterior surface of thelens, i.e., the surface adjacent to the vitreous body, is somewhatgreater than that of the anterior surface. The lens is closelysurrounded by a membranous capsule that serves as an intermediatestructure in the support and actuation of the lens. The lens and itscapsule are suspended on the optical axis behind the pupil by a circularassembly of very many radially directed elastic fibers, the zonules,which are attached at their inner ends to the lens capsule and at theirouter ends to the ciliary body and indirectly to the ciliary muscle, amuscular ring of tissue, located just within the outer supportingstructure of the eye, the sclera. The ciliary muscle is relaxed in theunaccommodated eye and therefore assumes its largest diameter. Accordingto the classical theory of accommodation, originating with Helmholtz,the relatively large diameter of the ciliary muscle in this conditioncauses a tension on the zonules which in turn pulls radially outward onthe lens capsule, causing the equatorial diameter of the lens toincrease slightly and decreasing the anterior-posterior dimension of thelens at the optical axis. Thus, the tension on the lens capsule causesthe lens to assume a flattened state wherein the curvature of theanterior surface, and to some extent the posterior surface, is less thanit would be in the absence of the tension. In this state the refractivepower of the lens is relatively low and the eye is focused for clearvision for distant objects.

When the eye is intended to be focused on a near object, the ciliarymuscles contract. According to the classical theory, this contractioncauses the ciliary muscle to move forward and inward, thereby relaxingthe outward pull of the zonules on the equator of the lens capsule. Thisreduced zonular tension allows the elastic capsule of the lens tocontract causing an increase in the antero-posterior diameter of thelens (i.e., the lens becomes more spherical) resulting in an increase inthe optical power of the lens. Because of topographical differences inthe thickness of the lens capsule, the central anterior radius ofcurvature decreases more than the central posterior radius of curvature.This is the accommodated condition of the eye wherein the image of nearobjects falls sharply on the retina.

Presbyopia is the universal decrease in the amplitude of accommodationthat is typically observed in individuals over forty years of age. Inthe person having normal vision, i.e., having emmetropic eyes, theability to focus on near objects is gradually lost, and the individualcomes to need glasses for tasks requiring near vision, such as reading.

According to the conventional view the amplitude of accommodation of theaging eye is decreased because of the loss of elasticity of the lenscapsule and/or sclerosis of the lens with age. Consequently, even thoughthe radial tension on the zonules is relaxed by contraction of theciliary muscles, the lens does not assume a greater curvature. Accordingto the conventional view, it is not possible by any treatment to restorethe accommodative power to the presbyopic eye. The loss of elasticity ofthe lens and capsule is seen as irreversible, and the only solution tothe problems presented by presbyopia is to use corrective lenses forclose work, or bifocal lenses, if corrective lenses are also requiredfor distant vision.

Contrary to the conventional view, it is possible to restore theaccommodative power to a presbyopic eye by implanting a plurality ofscleral prostheses within the sclera of the eye. For each individualscleral prosthesis an incision is made in the sclera of the globe of theeye near the plane of the equator of the crystalline lens. The incisionis then extended under the surface of the sclera to form a scleral“pocket.” The scleral prosthesis is then placed within the pocket. Atypical scleral prosthesis comprises a generally rectangularly shapedbar approximately five millimeters (5.0 mm) long, one and one halfmillimeters (1.5 mm) wide, and one millimeter (1.0 mm) tall. Theanterior edge of the scleral prosthesis applies an outward force on theanterior edge of the scleral pocket which elevates the anterior portionof the sclera attached thereto and the ciliary body immediately beneaththe sclera to increase the working distance of the ciliary muscle. Thismethod is described more fully in the “Presbyopia and Related EyeDisorder Patent Documents” that have been incorporated by reference intothis patent document.

A physician who makes the incisions to form a scleral pocket must be avery skilled surgeon. The surgeon must use great care to ensure that theincisions are made properly. The incisions that must be made to form ascleral pocket are quite small. The incisions must be made at preciselythe correct depth. The width and length of the scleral pocket must alsobe formed by very precise incisions.

It is well known that physicians may differ significantly with respectto the level of surgical skill that they possess. Physicians whopractice surgery regularly generally become quite skilled. Otherphysicians who do not practice surgery regularly are less skilled. Evenskilled surgeons may find it difficult to make the precise incisionsthat are required to correctly form a scleral pocket.

If scleral pocket incisions are not made with sufficient precision theresulting scleral pocket will not be able to correctly support a scleralprosthesis. An incorrectly supported scleral prosthesis is not able toprovide an acceptable level of vision correction.

A scleral pocket must be located on the sclera with sufficient precisionto ensure that a scleral prosthesis that is placed within the scleralpocket will be able to function correctly. An incorrectly locatedscleral pocket will not enable a scleral prosthesis to provide anacceptable level of vision correction.

It would be desirable if a system and method existed that would allow asurgeon to precisely locate an optimal position for forming a scleralpocket within the sclera of an eye. Accordingly, a need exists in theart for a system and method that is capable of precisely locating aposition on the sclera of an eye to form a scleral pocket to receive ascleral prosthesis.

SUMMARY OF THE INVENTION

The present invention comprises a system and method that is capable ofdetermining an optimal location on the sclera of an eye to form ascleral pocket to receive a scleral prosthesis.

The surgical tool for use with the system and method of the presentinvention comprises a base housing and a drive shaft housing. The basehousing of the surgical tool receives electrical power and controlsignals from an external surgical tool controller. The drive shafthousing comprises a blade mount housing that is mounted on the driveshaft housing at an angle to a central axis of the drive shaft housing.A rotatable blade for making incisions in the sclera of an eye ismounted on the blade mount housing.

A surgeon positions the rotatable blade of the surgical tool over thesclera of an eye. The surgeon determines the location of the scleralpocket by using information that is provided by the system and method ofthe present invention. The surgeon then places the blade mount housingon the sclera of the eye. A pressure sensor determines when there issufficient pressure between the surgical tool and the sclera of the eyefor the surgical tool to operate properly. When the pressure sensordetects sufficient pressure the surgical tool may be activated. Thesurgeon sends an activation signal to the surgical tool to cause therotatable blade to advance through the sclera to form an incision havingdimensions to receive a scleral prosthesis. The sclera of the eye andthe surgical tool are restrained from moving while the rotatable bladeis rotated through the sclera to make an incision. When the incision iscomplete the rotatable blade is rotated back out of the incision. Theincision then has the exact dimensions to receive a scleral prosthesis.

The apparatus of the present invention comprises a controller that iscapable, among other functions, of receiving eye measurements thatmeasure characteristics of the eye, such as a size of portions of aneye. The controller comprises a software processor and an eye modelapplication software program within the software processor. The eyemodel application software program uses the eye measurements to create amathematical model of the eye. The controller determines from themathematical model of the eye a location on the sclera of the eye thatis the optimum location for a scleral pocket to receive a scleralprosthesis.

It is an object of the invention to provide scleral pocket locationinformation to a surgeon who is operating a surgical tool that iscapable of making precise incisions in the sclera of an eye to create ascleral pocket that has exact dimensions to receive a scleralprosthesis.

It is an additional object of the invention to provide scleral pocketlocation information derived from measured values of corneal diameter,corneal radius of curvature, axial length of an eye, or the like.

It is yet another object of the invention to provide a system and methodfor providing precise location information to determine an optimallocation on the sclera of an eye for locating a scleral pocket toreceive a scleral prosthesis.

Additional objects of the present invention will become apparent fromthe description of the invention that follows.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention so that those skilled in the art maybetter understand the Detailed Description of the Invention thatfollows. Additional features and advantages of the invention will bedescribed hereinafter that form the subject matter of the claims of theinvention. Those skilled in the art should appreciate that they mayreadily use the conception and the specific embodiment disclosed as abasis for modifying or designing other structures for carrying out thesame purposes of the present invention. Those skilled in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the invention in its broadest form.

Before undertaking the Detailed Description of the Invention, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The terms “include” and “comprise,” andderivatives thereof, mean inclusion without limitation; the term “or” isinclusive, meaning “and/or”; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, to bound to orwith, have, have a property of, or the like; and the term “controller,”“processor,” or “apparatus” means any device, system or part thereofthat controls at least one operation. Such a device may be implementedin hardware, firmware or software, or some combination of at least twoof the same. It should be noted that the functionality associated withany particular controller may be centralized or distributed, whetherlocally or remotely. Definitions for certain words and phrases areprovided throughout this patent document. Those of ordinary skill shouldunderstand that in many instances (if not in most instances), suchdefinitions apply to prior uses, as well as to future uses, of suchdefined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view of an eye having scleral pockets forreceiving scleral prostheses;

FIG. 2 shows a front elevational view of an eye showing the location offour straight scleral pockets;

FIG. 3 shows a cross section of the eye of FIG. 2 along the line 3-3;

FIG. 4 shows an enlarged view of the cross section of FIG. 3 in theregion indicated by the circle 4;

FIG. 5 shows a top plan view of an exemplary scleral prosthesis;

FIG. 6 shows a front elevational view of the scleral prosthesis shown inFIG. 5 showing the contoured profile of the prosthesis and two notchesin the bottom of the prosthesis;

FIG. 7 shows a bottom plan view of the scleral prosthesis shown in FIG.5 showing the location of two notches in the bottom of the prosthesis;

FIG. 8 shows an end view of the scleral prosthesis shown in FIG. 5;

FIG. 9 shows a top perspective view of the scleral prosthesis shown inFIG. 5 showing the top and one side and one end of the prosthesis;

FIG. 10 shows a bottom perspective view of the scleral prosthesis shownin FIG. 5 showing the bottom and one side of the prosthesis;

FIG. 11 shows a perspective view of a surgical tool constructed formaking incisions in the sclera of an eye to create a scleral pocket toreceive a scleral prosthesis;

FIG. 12 shows a surgical tool controller for controlling the operationof the surgical tool of the present invention and a foot switch foractivating the surgical tool;

FIG. 13 shows an end view of the surgical tool of the present inventionshowing a control cable receptacle capable of receiving a control cableto supply electrical power to the surgical tool;

FIG. 14 shows a cross section of a first portion of the surgical toolshowing a base housing containing a control cable receptacle, a drivemotor, a gearbox, and a drive shaft capable of being rotated by thedrive motor;

FIG. 15 shows a schematic circuit diagram illustrating how electricalpower is supplied to the drive motor of the surgical tool;

FIG. 16 shows a cross section of a second portion of the surgical toolshowing a drive shaft housing mounted within an end of the base housingof the surgical tool, and showing a blade mount housing mounted on thedrive shaft housing an angle to a central axis of the drive shafthousing;

FIG. 17 shows a more detailed cross sectional view of theinterconnection of the drive shaft housing and the blade mount housingshown in FIG. 16;

FIG. 18 shows a top plan view of a blade of the surgical tool;

FIG. 19 shows a side view of the blade shown in FIG. 18;

FIG. 20 shows a perspective view of the blade shown in FIG. 18;

FIG. 21 shows a side view of the drive shaft housing and the blade mounthousing and the blade of the surgical tool;

FIG. 22 shows a perspective view of the drive shaft housing and an endview of the blade mount housing of the surgical tool;

FIG. 23 shows a top view illustrating how the surgical tool is to bepositioned over an eye to make incisions in the sclera of the eye;

FIG. 24 shows a side view illustrating how the surgical tool is to bepositioned over an eye to make incisions in the sclera of the eye;

FIG. 25 shows a perspective view of an alternate advantageous embodimentof a blade guide of the surgical tool to guide the motion of a bladewhen the blade is rotated to make incisions in the sclera of an eye;

FIG. 26 shows an end view of the blade guide shown in FIG. 25;

FIG. 27 shows an end view of the blade mount housing and blade guide andblade placed in contact with an eye showing how a blade passes throughthe blade guide when the blade is rotated to make incisions in thesclera of an eye;

FIG. 28 shows a side view of an end portion of the blade mount housingshowing a portion of the blade guide that is placed in contact with aneye during the process of making incisions in the sclera of the eye;

FIG. 29 shows how a blade moves through the blade guide shown in FIG. 28during the process of making incisions in the sclera of the eye;

FIG. 30 shows and exemplary scleral tissue fixation tool;

FIG. 31 shows a perspective view of an advantageous embodiment of afixation end of a scleral tissue fixation tool;

FIG. 32 shows a side view of an alternate advantageous embodiment of afixation end of a scleral tissue fixation tool;

FIG. 33 shows a side view of an alternative advantageous embodiment of ablade guide of the surgical tool comprising an interior vacuum chamber;

FIG. 34 shows a perspective view of the blade guide shown in FIG. 33;

FIG. 35 shows a side view of an alternative advantageous embodiment of ablade guide of the surgical tool comprising an interior vacuum chambershowing the operation of the vacuum chamber blade guide;

FIG. 36 shows a perspective view of a vacuum supply line coupled to thevacuum chamber blade guide;

FIG. 37 shows a perspective view of the surgical tool of the presentinvention showing the placement of a vacuum supply line along thesurgical tool;

FIG. 38 shows a flow chart of an advantageous embodiment of a method formaking incisions to form a scleral pocket for a scleral prosthesis;

FIG. 39 shows a flow chart of an alternate advantageous embodiment of amethod for making incisions to form a scleral pocket for a scleralprosthesis;

FIG. 40 shows a first perspective view of an alternate advantageousembodiment of a blade of the surgical tool;

FIG. 41 shows a second perspective view of an alternate advantageousembodiment of a blade of the surgical tool;

FIG. 42 shows how a scleral prosthesis may be tied to an extension of analternate advantageous embodiment of a blade of the surgical tool;

FIG. 43 shows a first perspective view of a second alternateadvantageous embodiment of a blade of the surgical tool;

FIG. 44 shows a second perspective view of a second alternateadvantageous embodiment of a blade of the surgical tool;

FIG. 45 shows a side view of three portions of a curved cutting blade ofthe second alternate advantageous embodiment of a blade of the surgicaltool;

FIG. 46 shows a first perspective view of a third alternate advantageousembodiment of a blade of the surgical tool;

FIG. 47 shows a second perspective view of a third alternateadvantageous embodiment of a blade of the surgical tool;

FIG. 48 shows a cross sectional side view of a curved cutting blade ofthe third alternate advantageous embodiment of a blade of the surgicaltool;

FIG. 49 illustrates a schematic representation of the geometry of thestructure of an eye;

FIG. 50 illustrates a schematic representation of distances betweencertain structures of the eye represented in FIG. 49;

FIG. 51 illustrates an applanation marking plate assembly;

FIG. 52 illustrates a controller that is capable of carrying out themethod of the present invention; and

FIG. 53 illustrates a flow chart showing one advantageous embodiment ofthe method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 through 53, discussed below, and the various embodiments used todescribe this principles of the present invention in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the invention. Those skilled in the artwill understand that the principles of the present invention may beimplemented in connection with any suitably arranged surgical tool andwith any suitable surgical method.

The system and method of the present invention is designed for use witha surgical tool that is capable of making incisions in the sclera of aneye in order for the eye to receive a scleral prosthesis. Scleralprostheses are used to treat presbyopia (and other similar eyedisorders) by increasing the effective working distance of the ciliarymuscle of the eye. This is accomplished by increasing the distancebetween the ciliary muscle and the lens equator by increasing thediameter of the sclera in the region of the ciliary body.

The effective working distance of the ciliary muscle is increased byimplanting in pockets surgically formed in the sclera of the eye aplurality of scleral prostheses designed to place an outward traction onthe sclera in the region of the ciliary body. The relevant anatomy ofthe eye for locating the scleral pockets may be seen by reference toFIGS. 1-4. The outermost layer of the eye 100 comprises the white, toughsclera 102 which encompasses most of the globe and the transparentcornea 104, which constitutes the anterior segment of the outer coat.The circular junction of the cornea and sclera is the limbus 106. Withinthe globe of the eye, as illustrated in the cross-section shown in FIG.3, the crystalline lens 108 is enclosed in a thin membranous capsule andis located immediately posterior to the iris 112, suspended centrallyposterior to the pupil 114 on the optical axis of the eye. The lens 108is suspended by zonules 115 extending between the lens capsule at theequator 110 of the lens 108 and the ciliary body 116. The ciliary body116 lies just under the sclera 102 (i.e., just inwardly of the sclera102) and is attached to the inner surface of the sclera 102. As may beseen in FIG. 3, the ciliary body 116 lies generally in a plane 130defined by the equator 110 of the lens 108. The plane 130 can also beextended to intersect the sclera 102 whereby it forms a generallycircular intersection located about two (2) millimeters posterior to thelimbus 106. The external muscles 118 of the eyeball control the movementof the eye.

A generally outwardly directed traction is exerted on the sclera in theregion of the ciliary body to expand the sclera 102 in that region. Thisexpansion of the sclera 102 produces a corresponding expansion of theattached ciliary body 116 and moves the ciliary body 116 outwardly awayfrom the equator 110 of the lens 108, generally in the plane 130 of theequator 110 of the lens 108. The sclera 102 is preferably expandedapproximately in the plane of the equator 110 of the lens 108. However,any expansion of the sclera 102 in the region of the ciliary body 116,i.e., in the region of the sclera somewhat anterior or posterior to theplane of the equator 110 of the lens 108 is within the scope of theinvention, provided that such expansion of the sclera 102 moves theciliary body 116 away from the equator 110 of the lens 108. Typically,the expansion of the sclera will be accomplished in the is region fromabout one and one half millimeters (1.5 mm) anterior to the plane 130 ofthe equator 110 of the lens 108 to about two and one half millimeters(2.5 mm) posterior to that plane, i.e., from about one half millimeter(0.5 mm) to about four and one half millimeters (4.5 mm) posterior tothe limbus 106. Accordingly, the anterior margin 122 of a scleral pocket120 will be located in that region of the sclera.

An exemplary scleral pocket 120 is illustrated in FIG. 1. An incision ismade in the surface of sclera 120 along the line indicated withreference numeral 131. The incision is then extended under the surfaceof sclera 120 between the anterior margin 122 and the posterior margin124 of scleral pocket 120. This forms a “pocket” under the surface ofsclera 102. The incision may also be extended through the surface ofsclera 102 along the line indicated with reference number 132. Thisforms a “belt loop” type structure in the surface of sclera 102. Forconvenience the “pocket” type structure and the “belt loop” typestructure will both be referred to as scleral pocket 120.

The scleral prosthesis 200 is designed to be placed within scleralpocket 120. Scleral prosthesis 200 within scleral pocket 120 applies anoutwardly directed traction to the sclera 102 at the general position ofthe anterior margin 122 of the scleral pocket 120. The position ofprosthesis 200 within scleral pocket 120 and its operation to expand thesclera are illustrated in FIGS. 3 and 4.

An advantageous embodiment of scleral prosthesis 200 is illustrated inFIGS. 5-10. FIG. 5 shows a plan view of the top 500 of prosthesis 200.In one advantageous embodiment, the length of prosthesis 200 isapproximately five thousand five hundred microns (5500 μm) or,equivalently, approximately five and one half millimeters (5.5 mm).

FIG. 6 shows a front elevational view of the prosthesis 200 of FIG. 5showing one side 600 of prosthesis 200. In one advantageous embodiment,the maximum height of prosthesis 200 is approximately nine hundredtwenty five microns (925 μm) or, equivalently, approximately ninehundred twenty five thousandths of a millimeter (0.925 mm). A firstnotch 610 is located in the base 620 of prosthesis 200 at a first end ofprosthesis 200. A second notch 630 is located in the base 620 ofprosthesis 200 at a second end of prosthesis 200. When prosthesis 200 islocated within scleral pocket 120 intraocular pressure from the interiorof eye 100 pushes scleral tissue into notch 610 and into notch 630. Thepresence of scleral tissue in notch 610 and in notch 630 provides ananchoring mechanism that tends to prevent movement of prosthesis 200.

FIG. 7 shows a plan view of the bottom 620 of prosthesis 200. Notch 610and notch 630 extend across the bottom 620 of prosthesis 200.

FIG. 8 shows an end view of prosthesis 200 showing one end 800 of theprosthesis 200. In one advantageous embodiment, the width of prosthesis200 is approximately one thousand three hundred eighty microns (1380 μm)or, equivalently, approximately one and three hundred eighty thousandthsmillimeter (1.380 mm).

FIG. 9 shows a perspective top view of prosthesis 200.

FIG. 9 shows top 500, one side 600 and one end 800 of the prosthesis200. FIG. 10 shows a perspective bottom view of prosthesis 200. FIG. 10shows the bottom 620 (including notches 610 and 630) and one side 600 ofprosthesis 200.

Other types of scleral prosthesis 200 may be used including those typesof prosthesis disclosed in the “Presbyopia and Related Eye DisorderPatent Documents” previously incorporated by reference into this patentdocument.

Scleral prosthesis 200 is made of a material that is sufficiently rigidto exert a force on the sclera sufficient to produce the radialexpansion required by the method of the invention and that isphysiologically acceptable for long-term implantation or contact withthe ocular tissues. Such materials are well-known in the surgical artand include suitable metals, ceramics, and synthetic resins. Suitablemetals include titanium, gold, platinum, stainless steel, nitinol,tantalum and various surgically acceptable alloys, and the like.Suitable ceramics may include crystalline and vitreous materials such asporcelain, alumina, silica, silicon carbide, high-strength glasses andthe like. Suitable synthetic materials include physiologically inertmaterials such as poly(methyl methacrylate), polyethylene,polypropylene, poly (tetrafluoroethylene), polycarbonate, siliconeresins, hydrophilic plastics, hydrophobic plastics, hypoxy-appetite, andthe like. The scleral prosthesis 200 may also be made of compositematerials incorporating a synthetic resin or other matrix reinforcedwith fibers of high strength material such as glass fibers, boron fibersor the like. Thus, scleral prosthesis 200 may be made ofglass-fiber-reinforced epoxy resin, carbon fiber-reinforced epoxy resin,carbon fiber-reinforced carbon (carbon-carbon), or the like. Scleralprosthesis 200 may be made of a semi-rigid exterior and a liquid or gelfilled interior so that the internal and external dimensions can bealtered by injecting various amounts of liquid: water, saline, orsilicone oil; or various amounts of a gel: silicone, collagen, orgelatin. The semi-rigid exterior may be made of any of the alreadylisted materials. A preferred material for the entire scleral prosthesis200 is surgical grade poly(methyl methacrylate). Scleral prosthesis 200may also be made of a material that regains its shape when deformed suchas a memory metal (e.g., nitinol).

Scleral prosthesis 200 may be manufactured by any conventional techniqueappropriate to the material used, such as machining, injection molding,heat molding, compression molding and the like.

Scleral prosthesis 200 may be foldable to facilitate insertion into ascleral belt loop or made in a plurality of parts so that it can beassembled prior to use or may be installed separately to form a completeprosthesis.

To implant scleral prosthesis 200 by hand, the surgeon locates theproper region of the sclera to be expanded by measuring a distance ofpreferably three and one half millimeters (3.5 mm) posterior of thelimbus 106. At two millimeters (2.0 mm) clockwise and counterclockwisefrom each of the forty five degree (450) meridians of the eye, and threeand one half millimeters (3.5 mm) posterior to the limbus 106, partialscleral thickness parallel incisions, i.e., antero-posterior incisions,are made which are one and one half millimeters (1.5 mm) long and threehundred fifty microns (350 μm) deep. Using a lamella blade the sclera isdissected until the partial thickness incisions are connected so thatfour scleral pockets or belt loops are made which have an anteriorlength of four millimeters (4.0 mm), and a length extending generallyaxially of the eye of one and one half millimeters (1.5 mm). Thus, eachpocket or belt loop is preferably centered over the forty five degree(450) meridian of the eye. A scleral prosthesis 200 is then inserted ineach of the four scleral belt loops. This produces symmetrical scleralexpansion which will produce the desired result of increasing theeffective working distance of the ciliary muscle.

The location of the scleral prostheses 200 implanted in eye 100 isillustrated in FIGS. 1-4. FIG. 1 is an isometric view of an eye 100having a globe with the relevant exterior anatomical parts indicated asdiscussed above.

FIG. 2 shows a front elevational view of an eye 100 showing the scleralpockets 120 formed at approximately the forty five degree (45°)meridians of the eye, i.e., approximately halfway between the verticaland horizontal meridians of the globe. This location is preferredbecause it avoids interference with structures of the eye that arelocated generally on the vertical and horizontal meridians. FIG. 2 showsthe use of straight scleral pockets 120. Straight scleral pockets 120are somewhat simpler to prepare surgically than curved scleral pockets(not shown). For many patients the use of straight scleral prosthesesprovide adequate treatment of presbyopia. Alternatively, curved scleralprostheses may be used as discussed in the “Presbyopia and Related EyeDisorder Patent Documents” previously incorporated by reference intothis patent document.

FIG. 3 shows a cross-section of eye 100, taken along the line 3-3 inFIG. 2, showing the placement of scleral prosthesis 200 relative to thesignificant anatomical structures of the eye.

FIG. 3 shows the general configuration of the scleral pockets 120 andthe prostheses 200 of the type illustrated in FIGS. 5-10. The anteriormargins 122 of the scleral pockets 120 are located approximately in theplane 130 of the equator 110 of the lens 108. The presence of prosthesis200 causes the portion of the sclera anterior to the scleral pocket 120to be expanded somewhat more than the posterior portion. This places thesclera anterior to the scleral pocket 120 under a radial tension andcauses it to expand from its normal diameter at that position. Thisscleral expansion draws with it the underlying ciliary body 116 andcauses the ciliary body to be drawn away from the equator 110 of thelens 108. Accordingly, the expansion of the ciliary body 116 operates toincrease the working distance of the ciliary muscle and restore, atleast in part, the ability of the eye to accommodate for clear focusingon objects at different distances.

FIG. 4 shows an enlarged portion of one of the scleral pockets 120 withadjacent anatomical structures. It shows the relation of the scleralpocket 120 to the underlying structures and its location just posteriorto the equator of the lens 108 and overlying the ciliary body 116.

The surgical procedures described above to make incisions within thesclera 102 of eye 100 are done by hand. That is, the surgeon makes theincisions in sclera 102 that are required to form scleral pocket 120using standard surgical tools such as a scalpel. The surgeon must bevery skilled in the use of a scalpel to make incisions that have therequired precision.

However, the system and method of the present invention provide a muchmore efficient and precise way to determine the optimum location for therequired incisions. The system and method of the present invention isdesigned for use with a surgical tool that is specifically designed tomake very precise incisions in the sclera 102 of an eye 100 to form ascleral pocket 120.

FIG. 11 shows a perspective view of a surgical tool 1100. As will bemore fully described, surgical tool 1100 is capable of making incisionsin eye 100 to create a scleral pocket 120 to receive a scleralprosthesis 200 surgical tool 1100 comprises a base housing 1110 and adrive shaft housing 1120. Drive shaft housing 1120 comprises a blademount housing 1130 that mounted on the drive shaft housing 1120 an angleto a central axis of drive shaft housing 1120. The reason for mountingblade mount housing 1130 at an angle with respect to the central axis ofdrive shaft housing 1120 is to facilitate the placement of blade mounthousing 1130 on eye 100 during the surgical process. Lastly, blade 1140is mounted on blade mount housing 1130.

FIG. 12 shows surgical tool 1100 and a surgical tool controller 1200 forcontrolling the operation of surgical tool 1100. Surgical tool 1100 iscoupled to surgical tool controller 1200 through control cable 1210.Control cable 1210 provides electrical power to surgical tool 1100 underthe control of surgical tool controller 1200 to power the operation ofblade 1140. Control cable 1210 also provides an “earth ground” tosurgical tool 1100. Surgical tool controller 1200 receives externalelectrical power through power cord 1220.

Foot switch 1230 is coupled to surgical tool controller 1200 throughsignal line 1240. When the surgeon is ready to rotate blade 1140 to makean incision in eye 100 the surgeon steps on foot switch 1230. Footswitch 1230 then sends a control signal to surgical tool controller 1200through signal line 1240. In response, surgical tool controller 1220activates electrical power to surgical tool 1100 to cause blade 1140 torotate in a forward direction and make the desired incision in eye 100.The time required for blade 1140 to make an incision in eye 100 isapproximately two (2) seconds. The incision is complete after blade 1140has reached the end of its rotation in the forward direction. Surgicaltool controller 1200 then automatically causes blade 1140 to rotate backout of the incision. Surgical tool 1100 is then ready to make anotherincision.

If the surgeon releases his or her foot from foot switch 1230 during thetwo (2) second time period during which the incision is being made, footswitch 1230 immediately sends a control signal to surgical toolcontroller 1200 through signal line 1240. In response, surgical toolcontroller 1220 causes the forward motion of blade 1140 to cease andthen automatically rotates blade 1140 out of the incision.

Surgical tool controller 1200 comprises a switch 1250 (on/off switch1250) for activating the operation of surgical tool controller 1200.Surgical tool controller 1200 also comprises indicator lights 1260 thatindicate the operational status of surgical tool controller 1200.

FIG. 13 shows an end view of base housing 1110 of surgical tool 1100.Base housing 1110 comprises a control cable receptacle 1300 capable ofreceiving control cable 1210 to electrically power surgical tool 1100.In this advantageous embodiment control cable receptacle 1300 is capableof receiving four (4) individual power plugs of control cable 1210.

FIG. 14 shows a cross section of base housing 1110. Base housing 1110comprises control cable receptacle 1300, four power lines (collectivelydesignated 1410), drive motor 1420, gearbox 1430, and a drive shaft1440. When control cable 1210 is placed into control cable receptacle1300, four power plugs of control cable 1210 make contact with the fourpower lines 1410. As shown in FIG. 15, two of the four power lines (line1 and line 2) are coupled to a first winding circuit (circuit A) ofmotor 1420. The other two of the four power lines (line 3 and line 4)are coupled to a second winding circuit (circuit B) of motor 1420.

When surgical tool controller 1200 powers up line 1 and line 2, thenmotor 1420 rotates in one direction (e.g., counterclockwise). Whensurgical tool controller 1200 powers up line 3 and line 4, then motor1420 rotates in the other direction (e.g., clockwise). In this mannermotor 1420 provides both rotational motion to rotate blade 1140 forwardto make an incision in eye 100 and provides rotational motion to rotateblade 1140 backwards to remove blade 1140 from the incision made in eye100. The two types of rotational motion will be collectively referred toas “bidirectional rotational motion.”

The rotational motion generated by motor 1420 is coupled to gearbox1430. In one advantageous embodiment gearbox 1430 reduces the rotationalspeed provided by motor 1420 by a factor of sixty six (66:1). That is,the rotational speed output by gearbox 1430 is one sixty sixth ( 1/66)of the rotational speed provided to gearbox 1430 by motor 1420. Thisamount of rotational speed reduction is necessary to increase the torqueand because the rotational speed provided by motor 1420 is too great tobe used to rotate blade 1140 directly. The rotational output fromgearbox 1430 is coupled to drive shaft 1440 of base housing 1110.

FIG. 16 shows a cross sectional view of drive shaft housing 1120 mountedwithin base housing 1110 and a cross sectional view of blade mounthousing 1130. Blade 1140 is not shown in FIG. 16. Drive shaft housing1120 seats within a receptacle of base housing 1110 and is held in placeby conventional means such as a screw 1610. O-ring 1620 seals thejuncture between the receptacle of base housing 1110 and drive shafthousing 1120.

Drive shaft housing 1120 comprises drive shaft 1630. Drive shaft 1630 issupported within drive shaft housing 1120 by conventional bearings. Asshown in FIG. 16, drive shaft 1630 is coupled to drive shaft 1440 ofbase housing 1110. The coupling of drive shaft 1630 and drive shaft 1440is supported by conventional bearings. Drive shaft 1440 rotates driveshaft 1630.

Blade mount housing 1130 comprises drive shaft 1640. Drive shaft 1640 issupported within blade mount housing 1130 by conventional bearings. Asshown in FIG. 16, drive shaft 1640 is coupled to drive shaft 1630 ofdrive shaft housing 1120 at an angle. As shown in greater detail in FIG.17, a beveled gear 1710 of drive shaft 1630 engages a beveled gear 1720of drive shaft 1640. As drive shaft 1630 is rotated, the rotationalmotion of beveled gear 1720 of drive shaft 1630 is imparted to beveledgear 1720 of drive shaft 1640. The rotational motion of drive shaft 1640is used to rotate blade 1140 (not shown in FIGS. 16 and 17) mounted onblade mount housing 1130.

Base plate 1730 seats within an end of blade mount housing 1130 and isheld in place by conventional means such as a screw 1740. Drive shaft1640 extends through an aperture in base plate 1730 so that base plate1730 also provides support for drive shaft 1640. Conventional means suchas a screw 1750 may be used to secure blade 1140 to drive shaft 1640.Screw 1750 may also serve as an extension 1750 of drive shaft 1640 ontowhich blade 1140 may be mounted. Base plate 1730 comprises portionsforming a blade guide 1760 for guiding the rotation of blade 1140 andfor stopping the rotation of blade 1140 after blade 1140 has beenrotated by a desired amount.

The blade 1140 of surgical tool 1100 is shown in FIGS. 18-20. FIG. 18shows a top plan view of blade 1140. FIG. 19 shows a side view of blade1140. FIG. 20 shows a perspective view of blade 1140. Blade 1140comprises support arm 1810 adapted to be mounted on an end of driveshaft 1640 of blade mount housing 1130. Blade 1140 also comprises acurved cutting blade 1820 for making an incision in the sclera 102 ofeye 100. In an advantageous embodiment of the invention, (1) support arm1810 and curved cutting blade 1820 are formed as a unitary structure,and (2) curved cutting blade 1820 is circularly curved, and (3) curvedcutting blade 1820 has end portions defining a tapered cutting point1830.

When drive shaft 1640 is rotated, support arm 1810 rotates around theaxis of drive shaft 1640. This causes curved cutting blade 1820 torotate around the axis of drive shaft 1640. The dimensions of curvedcutting blade 1820 are chosen so that the incision made by curvedcutting blade 1820 in the sclera 102 of eye 100 has the desireddimensions to form scleral pocket 120. Scleral pocket 120 should beapproximately four millimeters (4.0 mm) long, one and one halfmillimeters (1.5 mm) wide, and four hundred microns (400 μm) deep. Fourhundred microns (400 μm) is equivalent to four tenths of a millimeter(0.4 mm).

FIG. 21 shows an external side view of drive shaft housing 1120 andblade mount housing 1130 and blade 1140. Aperture 2110 is provided toreceive screw 1610 to fasten drive shaft housing 1120 within basehousing 1110. Groove 2120 is provided to receive O-ring 1620 to seal thejuncture between the receptacle of base housing 1110 and drive shafthousing 1120. Aperture 2130 is provided to receive screw 1740 to fastenbase plate 1730 within blade mount housing 1130.

An external reference line 2140 is marked on the surface of blade mounthousing 1130. Line 2140 is located five and one half millimeters (5.5mm) from the end of blade mount housing 1130. Line 2140 allows thesurgeon to properly align blade 1140 during the surgical process. Thesurgeon aligns line 2140 with the limbus 106 of eye 100. This alignmentproperly positions blade 1140 to make an incision at the desiredlocation on sclera 102 of eye 100.

FIG. 22 shows a perspective view of drive shaft housing 1120 and an endview of blade mount housing 1130. Base plate 1730 forms the end of blademount housing 1130. The components of blade 1140 are shown separately assupport arm 1810 and curved cutting blade 1820. Support arm 1810 ismounted on drive shaft 1640 by snapping an end of support arm 1810 ontoan extension 1750 of drive shaft 1640. In an alternative embodiment,support arm 1810 may be mounted on drive shaft 1640 using conventionalmeans such as a screw.

Support arm 1810 is shown rotated forward to a position where it hasabutted an edge of blade guide 1760. In this position curved cuttingblade 1820 has completed its rotation and would have completed anincision if it has been adjacent to eye 100. Blade guide 1760 alsoguides the rotation of blade 1140. Blade guide 1760 is formed having acircularly shaped surface 2220 that is concentric with curved cuttingblade 1820. The length of support arm 1810 supports curved cutting blade1820 at a distance that is approximately four hundred microns (400 μm)away from the circularly shaped surface 2220 of blade guide 1760.

At the start of the surgical process the surgeon places the circularlyshaped surface 2220 of blade guide 1760 on the sclera 102 of eye 100.The surgeon then begins the rotation of blade 1140 by stepping on footswitch 1230. As long as the surgeon is stepping on foot switch 1230blade 1140 continues to advance in a forward direction as support arm1810 of blade 1140 rotates curved cutting blade 1820. Curved cuttingblade 1820 then passes through sclera 102 of eye 100 at a depth ofapproximately four hundred microns (400 μm) to make the desiredincision. The surgeon removes his or her foot from foot switch 1230 ifthe surgeon determines that it is desirable to stop the rotation ofblade 1140. Surgical tool controller 1200 will immediately stop therotation of blade 1140 and will then automatically rotate blade 1140 outof the incision.

The components of blade 1140 (support arm 1810 and curved cutting blade1820) may also be rotated back to abut the safety stop 2210. Blade guide1760 and safety stop 2210 limit the rotational range of blade 1140 toonly the rotation needed to perform the desired incisions.

FIG. 23 shows a top view illustrating how surgical tool 1100 is to bepositioned over eye 100 to make incisions in the sclera 102 of eye 100.Eye 100 comprises sclera 102, iris 112, pupil 114, and limbus 106 (theboundary between sclera 102 and iris 112). Iris 114 and portions oflimbus 106 are shown in dotted outline in FIG. 23 because they areobscured by drive shaft housing 1120 and blade mount housing 1130. Aspreviously mentioned, the surgeon aligns line 2140 on blade mounthousing 1130 with the limbus 106 of eye 100. This alignment properlypositions blade 1140 to make an incision at the desired location onsclera 102 of eye 100.

FIG. 24 shows a side view illustrating how surgical tool 1100 is to bepositioned over eye 100 to make incisions in the sclera 102 of eye 100.The surgeon aligns line 2140 on blade mount housing 1130 with limbus 106of eye 100. As described with reference to FIG. 23 this alignmentproperly positions blade 1140. The reason for mounting blade mounthousing 1130 at an angle with respect to the central axis of drive shafthousing 1120 is now apparent. It is to facilitate the placement of blademount housing 1130 on eye 100 during the surgical process.

FIG. 25 shows a perspective view of an alternate advantageous embodiment2500 of blade guide 1760. Blade guide 2500 is mounted on base plate1730. In this embodiment blade guide 2500 comprises an end portion 2510forming a first blade slot 2520 on a first end of blade guide 2500.Blade guide 2500 also comprises an end portion 2530 forming a secondblade slot 2540 on a second end of blade guide 2500. Blade guide 2500operates in the same manner as blade guide 1760 except that the endportions, 2510 and 2530, of blade guide 2500 provide additional externalprotection for curved cutting blade 1820 of blade 1140. End portions,2510 and 2530, may also be seated against sclera 102 of eye 100 duringthe surgical process to provide additional peripheral contact betweenblade guide 2500 and sclera 102 and to ensure a proper length for anincision.

FIG. 26 shows an end view of blade guide 2500. Blade guide 2500 isformed having a circularly shaped surface 2550 that is concentric withcurved cutting blade 1820. The length of support arm 1810 supportscurved cutting blade 1820 at a distance that is approximately fourhundred microns (400 μm) away from the circularly shaped surface 2550 ofblade guide 2500.

At the start of the surgical process the surgeon places circularlyshaped surface 2550 of blade guide 2500 on the sclera 102 of eye 100. Apressure sensor 2560 within blade guide 2500 senses the pressure of thesclera 102 against the circularly shaped surface 2550 of blade guide2500. A pressure sensor control line (not shown) connects pressuresensor 2560 to surgical tool controller 1200. Pressure sensor 2560senses whether there is sufficient pressure between the surface ofsclera 102 and the circularly shaped surface 2550 of blade guide 2500.If there is not sufficient pressure then any incision made by blade 1140would be too shallow. If pressure sensor 2560 does not detect sufficientpressure then surgical tool controller 1200 will not allow blade 1140 ofsurgical tool 1100 to rotate. If pressure sensor 2560 does detectsufficient pressure then surgical tool controller 1200 will allow blade1140 of surgical tool 1100 to rotate.

The surgeon begins the rotation of blade 1140 by stepping on foot switch1230. As long as the surgeon is stepping on foot switch 1230 blade 1140continues to advance in a forward direction as support arm 1810 of blade1140 rotates curved cutting blade 1820. Curved cutting blade 1820 thenpasses through sclera 102 of eye 100 at a depth of approximately fourhundred microns (400 μm) to make the desired incision. The surgeonremoves his or her foot from foot switch 1230 if the surgeon determinesthat it is desirable to stop the rotation of blade 1140. Surgical toolcontroller 1200 will immediately stop the rotation of blade 1140 andwill then automatically rotate blade 1140 out of the incision.

FIG. 27 shows an end view of blade guide 2500 showing how curved cuttingblade 1820 passes through first blade slot 2520 of blade guide 2500, andthrough sclera 102 of eye 100, and through second blade slot 2540 ofblade guide 2500 when support arm 1810 of blade 1140 is rotated. Curve2710 represents the surface contour of sclera 102 of eye 100 beforeblade guide 2500 is placed in contact with eye 100. Curve 2720represents the surface contour of eye 100 after blade guide 2500 isplaced in contact with sclera 102 of eye 100. Pressure applied to keepblade guide 2500 in contact with sclera 102 of eye 100 temporarily makesthe surface contour of the sclera 102 of eye 100 concave during theincision process.

FIG. 28 shows a side view of an end portion of blade mount housing 1130showing the surface 2550 of blade guide 2500 that is placed in contactwith sclera 102 of eye 100. Pressure sensor 2560 in blade guide 2500 isshown in dotted outline. In this view curved cutting blade 1820 of blade1140 is retracted. First blade slot 2520 and second blade slot 2540 ofblade guide 2500 are visible.

FIG. 29 also shows a side view of an end portion of blade mount housing1130 showing the surface 2550 of blade guide 2500 that is placed incontact with sclera 102 of eye 100. As before, pressure sensor 2560 inblade guide 2500 is shown in dotted outline. In this view curved cuttingblade 1820 of blade 1140 has begun to be rotated through first bladeslot 2520. Curved cutting blade 1820 is the process of rotating acrosssurface 2550 of blade guide 2500 and is proceeding toward second bladeslot 2540 of blade guide 2500. FIG. 29 shows how curved cutting blade1820 moves through blade guide 2500 during the process of makingincisions in sclera 102 of eye 100.

The counterclockwise motion of the curved cutting blade 1820 hitting thesurface of the sclera 102 of eye 100 tends to push surgical tool 1100 inthe opposite direction causing surgical tool 1100 to translate oppositeto the tangent force generated by curved cutting blade 1820. It istherefore necessary to firmly hold the surface of the sclera 102 againstthe surgical tool 1100 during the process of making the incision.

In one advantageous embodiment of the invention, a scleral tissuefixation tool 3000 is utilized to restrain the movement of surgical tool1100. As shown in FIG. 30, scleral tissue fixation tool 3000 generallycomprises a shaft 3010 having a fixation end 3020 that is capable ofengaging and holding a portion of the surface of sclera 102. Scleraltissue fixation tool 3000 applies a force opposite to the tangent forcegenerated by the curved cutting blade 1820 coming in contact with thesclera 102. The shaft 3010 is manually held and operated by the surgeonduring the process of making an incision so that surgical tool 1100 doesnot move.

In one advantageous embodiment, scleral tissue fixation tool 3000 isapproximately fifteen centimeters (15.0 cm) to twenty centimeters (20.0cm) long and approximately one and one half millimeters (1.5 mm) wide.FIG. 31 shows a perspective view of fixation end 3020 of scleral tissuefixation tool 3000. Fixation end 3020 comprises a first fixation barb3110 formed on a first side of the end of shaft 3010. First fixationbarb 3110 is formed by slicing and lifting up an end portion of shaft3010. The amount of separation of first fixation barb 3110 from the endof shaft 3010 is in the range from three tenths of a millimeter (0.30mm) to four tenths of a millimeter (0.40 mm).

Fixation end 3020 also comprises a second fixation barb 3120 formed on asecond side of the end of shaft 3010. Second fixation barb 3120 isformed by slicing and lifting up an end portion of shaft 3010. Theamount of separation of second fixation barb 3120 from the end of shaft3010 is the same as the amount of separation of first fixation barb3110.

To restrain the translational movement of surgical tool 1100 the surgeonuses scleral tissue fixation tool 3000 to engage and hold a portion ofsclera 102 near the first blade slot 2520 of blade guide 2500. Firstblade slot 2520 is where curved cutting blade 1820 first impacts sclera102 and tends to cause translation of surgical tool 1100. The surgeonplaces the fixation end 3020 of the scleral tissue fixation tool 3000onto the sclera 102 and twists shaft 3010 to the right to engage firstfixation barb 3110 and second fixation barb 3120 into sclera 102. Thesurgeon holds the shaft 3010 against surgical tool 1100 during theincision process. After the incision has been made the surgeon releasesthe scleral tissue fixation tool 3000 from sclera 102 by twisting shaft3010 to the left to disengage the grip of fixation barbs, 3110 and 3120.

The scleral tissue fixation tool 3000 shown in FIG. 31 is a “righttwist” tool. It engages by twisting shaft 3010 to the right anddisengages by twisting shaft 3010 to the left.

FIG. 32 shows an alternative advantageous embodiment of scleral tissuefixation tool 3000. The scleral tissue fixation tool 3000 shown in FIG.32 is a “left twist” tool. It engages by twisting shaft 3010 to the leftand disengages by twisting shaft 3010 to the right. Otherwise, thescleral tissue fixation tool 3000 shown in FIG. 32 is identical to thescleral tissue fixation tool 3000 shown in FIG. 31. It comprises a firstfixation barb 3210 and a second fixation barb 3220. The amount ofseparation 3230 of first fixation barb 3210 from the end of shaft 3010is in the range from three tenths of a millimeter (0.30 mm) to fourtenths of a millimeter (0.40 mm). The amount of separation of secondfixation barb 3220 from the end of shaft 3010 is the same as the amountof separation of first fixation barb 3210.

In an alternate advantageous embodiment of the invention, a special typeof vacuum operated blade guide 3300 is utilized to restrain the movementof the sclera 102 and the translational movement of surgical tool 1100generated from the impact of the curved cutting blade 1820. As will bemore fully described, a vacuum is applied to seat blade guide 330against sclera 102 during the process of making an incision.

FIG. 33 shows an end view of blade guide 3300. Blade guide 3300 ismounted on base plate 1730. In this embodiment blade guide 3300comprises an end portion 3310 forming a first blade slot 3320 on a firstend of blade guide 3300. Blade guide 3300 also comprises an end portion3330 forming a second blade slot 3340 on a second end of blade guide3300. The end portions, 3310 and 3330, of blade guide 3300 provideadditional external protection for curved cutting blade 1820 of blade1140. End portions, 3310 and 3330, are seated against sclera 102 of eye100 during the surgical process to provide additional peripheral contactbetween blade guide 3300 and sclera 102 to ensure proper scleral pocketlength.

Blade guide 3300 is formed having a circularly shaped surface 3350 thatis concentric with curved cutting blade 1820. The length of support arm1810 supports curved cutting blade 1820 at a distance that isapproximately four hundred microns (400 μm) away from the circularlyshaped surface 3350 of blade guide 3300.

At the start of the surgical process the surgeon places circularlyshaped surface 3350 of blade guide 3300 on the sclera 102 of eye 100. Apressure sensor 3390 within blade guide 3300 senses the pressure of thesclera 102 against the circularly shaped surface 3350 of blade guide3300. A pressure sensor control line (not shown) connects pressuresensor 3390 to surgical tool controller 1200. Pressure sensor 3390senses whether there is sufficient pressure between the surface ofsclera 102 and the circularly shaped surface 3350 of blade guide 3300.If there is not sufficient pressure then any incision made by blade 1140would be too shallow. If pressure sensor 3390 does not detect sufficientPressure then surgical tool controller 1200 will not allow blade 1140 ofsurgical tool 1100 to rotate. If pressure sensor 3390 does detectsufficient pressure then surgical tool controller 1200 will allow blade1140 of surgical tool 1100 to rotate.

The surgeon begins the rotation of blade 1140 by stepping on foot switch1230. As long as the surgeon is stepping on foot switch 1230 blade 1140continues to advance in a forward direction as support arm 1810 of blade1140 rotates curved cutting blade 1820. Curved cutting blade 1820 thenpasses through sclera 102 of eye 100 at a depth of approximately fourhundred microns (400 μm) to make the desired incision. The surgeonremoves his or her foot from foot switch 1230 if the surgeon determinesthat it is desirable to stop the rotation of blade 1140. Surgical toolcontroller 1200 will immediately stop the rotation of blade 1140 andwill then automatically rotate blade 1140 out of the incision.

Blade guide 3300 also comprises portions that form a vacuum chamber 3360within the interior of blade guide 3300. Blade guide 3300 also comprisesportions that form a plurality of access ports, 3365, 3370, and 3375,that extend from vacuum chamber 3360 through the circularly shapedsurface 3350 of blade guide 3300 to apply vacuum to the surface ofsclera 102. Blade guide 3300 also comprises a vacuum coupling 3380capable of being connected to a vacuum supply line (not shown in FIG.33).

FIG. 34 shows a perspective view of blade guide 3300 showing end portion3310 and first blade slot 3320. FIG. 34 also shows end portion 3330 andsecond blade slot 3340. Vacuum coupling 3380 extends from the exteriorof blade guide 3300 to vacuum chamber 3360 (not shown in FIG. 34)located within blade guide 3300.

FIG. 35 shows an end view of blade guide 3300 showing the placement ofcircularly shaped surface 3350 of blade guide 3300 on the surface ofsclera 102. For clarity end portion 3310, first blade slot 3320, endportion 3330 and second blade slot 3340 previously shown in FIG. 34 havebeen omitted from FIG. 35.

Vacuum coupling 3380 is coupled to a vacuum supply line 3500. Vacuumsupply line 3500 provides a vacuum to vacuum chamber 3360. The vacuumcauses air to pass through access ports 3365, 3370, and 3375 into vacuumchamber 3360 (shown by arrows in FIG. 35) when access ports 3365, 3370,and 3375 are open to the atmosphere. When circularly shaped surface 3350of blade guide 3300 is placed in contact with the surface of sclera 102the vacuum in vacuum chamber 3360 causes sclera 102 to adhere to thesurface of circularly shaped surface 3350. The adhesion caused by thevacuum in vacuum chamber 3360 restrains the movement of sclera 102 whencurved cutting blade 1820 is rotated into sclera 102 to make anincision.

This alternate advantageous embodiment requires vacuum supply line 3500be to connected to a vacuum supply (not shown). FIG. 36 shows how vacuumsupply line 3500 is connected to vacuum coupling 3380 of blade guide3300. FIG. 37 shows how vacuum supply line 3500 may be externallylocated along the length of surgical tool 1100.

FIG. 38 shows a flow chart of an advantageous embodiment of a method formaking incisions to form a scleral pocket 120 for a scleral prosthesis200. The steps of the method are generally denoted with referencenumeral 3800. Blade mount housing 1130 of surgical tool 1100 ispositioned over sclera 102 of eye 100 by aligning external referenceline 2140 of blade mount housing 1130 with limbus 106 of eye 100 (step3810). Then blade mount housing 1130 and blade 1140 are placed intocontact with sclera 102 (step 3820).

The movement of sclera 102 and surgical tool 1100 is then restrained byengaging and holding sclera 102 with scleral tissue fixation tool 3000(step 3830). Surgical tool 1100 rotates curved cutting blade 1820through sclera 102 to make an incision to form scleral pocket 120 (step3840). When the incision is complete surgical tool 110 rotates curvedcutting blade 1820 back out of the incision made through sclera 102(step 3850). Then sclera 102 is released by disengaging scleral tissuefixation tool 3000 (step 3860). The incision forms scleral pocket 120 toreceive scleral prosthesis 200.

FIG. 39 shows a flow chart of an alternate advantageous embodiment of amethod for making incisions to form a scleral pocket 120 for a scleralprosthesis 200. The steps of the method are generally denoted withreference numeral 3900. Blade mount housing 1130 of surgical tool 1100is positioned over sclera 102 of eye 100 by aligning external referenceline 2140 of blade mount housing 1130 with limbus 106 of eye 100 (step3910). Then blade mount housing 1130 and blade 1140 are placed intocontact with sclera 102 (step 3920).

The movement of sclera 102 and surgical tool 1100 is then restrained byengaging and holding sclera 102 with a vacuum from vacuum chamber 3360of blade guide 33000 (step 3930). Surgical tool 1100 rotates curvedcutting blade 1820 through sclera 102 to make an incision to formscleral pocket 120 (step 3940). When the incision is complete surgicaltool 110 rotates curved cutting blade 1820 back out of the incision madethrough sclera 102 (step 3950). Then sclera 102 is released by ventingthe vacuum in vacuum chamber 3360 of blade guide 3300 (step 3960). Theincision forms scleral pocket 120 to receive scleral prosthesis 200.

FIG. 40 shows a first perspective view of an alternate advantageousembodiment of blade 1140 of surgical tool 1100 of the present inventioncomprising support arm 4010 and curved cutting blade 4020. In theembodiment of blade 1140 shown in FIGS. 18-20 support arm 1810 andcurved cutting blade 1820 are formed as a unitary structure. In theembodiment of blade 1140 shown in FIG. 40 curved cutting blade 4020 isdetachable from support arm 4010.

FIG. 41 shows a second perspective view of the alternate advantageousembodiment of blade 1140 shown in FIG. 40. Curved cutting blade 4020comprises an extension 4030 having portions that form an aperture 4040through extension 4030. As shown in FIG. 42, a string-like connector4200 (e.g., a plastic fiber 4200) may be used to tie a scleralprosthesis 200 to extension 4030. Surgical tool 1100 rotates support arm4010 and causes curved cutting blade 4020 to pass through sclera 102 aspreviously described.

However, in this advantageous embodiment of the invention curved cuttingblade 4020 is disconnected from support arm 4010 after the incision insclera 102 has been made. Curved cutting blade 4020 remains within theincision. Surgical tool 1100 is removed. Then the leading edge of curvedcutting blade 4020 is withdrawn from the incision in the forwarddirection. Because curved cutting blade 4020 is tied to scleralprosthesis 200 by string-like connector 4200 the withdrawal of curvedcutting blade 4020 from the incision pulls scleral prosthesis 200 intothe incision. Curved cutting blade 4020 acts as a needle pulling thestring-like connector 4200. Curved cutting blade 4020 is thenre-attached to support arm 4010 for use in making the next incision ofsclera 102.

FIG. 43 shows a first perspective view of a second alternateadvantageous embodiment of blade 1140 of surgical tool 1100 of thepresent invention comprising support arm 4310 and curved cutting blade4320. In the embodiment of blade 1140 shown in FIGS. 18-20 support arm1810 and curved cutting blade 1820 are formed as a unitary structure. Inthe embodiment of blade 1140 shown in FIG. 43 curved cutting blade 4320is detachable from support arm 4310.

In addition a central portion 4330 of curved cutting blade 4320 isdetachable from the other portions of curved cutting blade 4320. Curvedcutting blade 4320 comprises three portions. The three portions are (1)detachable central portion 4330, and (2) detachable tip 4340, and (3)blade portion 4350. FIG. 44 shows a second perspective view of thesecond alternate advantageous embodiment of blade 1140 shown in FIG. 43.Central portion 4330 is shown shaded in FIGS. 43 and 44.

Curved cutting blade 4320 is rotated into sclera 102 to form an incisionin the manner previously described. The curved cutting blade 4320 isdetached from support arm 4310 while curved cutting blade 4320 remainswithin the incision. FIG. 45 shows a side view of the three portions(4330, 4340, 4350) of curved cutting blade 4320 within an incision.

Then detachable tip 4340 is detached from detachable central portion4330 (e.g., by forceps) and is removed from the incision. Then bladeportion 4350 is detached from detachable central portion 4330 and isremoved from the incision. Detachable central portion 4330 is leftwithin the incision to serve as a scleral prosthesis 200.

FIG. 46 shows a first perspective view of a third alternate advantageousembodiment of blade 1140 of surgical tool 1100 comprising support arm4610 and curved cutting blade 4620. In the embodiment of blade 1140shown in FIGS. 18-20 support arm 1810 and curved cutting blade 1820 areformed as a unitary structure. In the embodiment of blade 1140 shown inFIG. 46 curved cutting blade 4620 is detachable from support arm 4610.

In addition curved cutting blade 4620 has portions that define a conduit4630 through curved cutting blade 4620. Slidably disposed within conduit4630 is scleral prosthesis 200. Plunger 4640 is also slidably disposedwithin conduit 4630. Plunger 4630 abuts scleral prosthesis 200. FIG. 47shows a second perspective view of the third alternate advantageousembodiment of blade 1140 shown in FIG. 46. Scleral prosthesis 200 isshown shaded in FIGS. 46 and 47.

Curved cutting blade 4620 is rotated into sclera 102 to form an incisionin the manner previously described. The curved cutting blade 4620 isdetached from support arm 4610 while curved cutting blade 4620 remainswithin the incision. FIG. 48 shows a cross sectional side view of curvedcutting blade 4620. Curved cutting blade 4620 is withdrawn from theincision. Plunger 4640 remains in place against scleral prosthesis 200as curved cutting blade 4620 is withdrawn from the incision. Plunger4640 prevents scleral prosthesis 200 from being withdrawn from theincision. Plunger 4640 finally pushes scleral prosthesis 200 out ofconduit 4630 and into the incision. Then plunger 4640 is withdrawn fromthe incision leaving scleral prosthesis 200 properly placed within theincision.

In one advantageous embodiment, scleral prosthesis 200 is capable ofbeing filled with a fluid. Scleral prosthesis 200 is filled with a fluidafter scleral prosthesis 200 has been placed within the incision inorder to increase the size of scleral prosthesis 200.

FIG. 49 illustrates a schematic representation of the geometry of thestructure of eye 100. FIG. 50 illustrates a schematic representation ofdistances between certain structures of eye 100. The system and methodof the present invention for determining a position for scleral pocket120 in the sclera 102 of eye 100 will be described with reference to thegeometry of the structures of eye 100 shown in FIG. 49 and in FIG. 50.

A cross section of eye 100 is represented by two intersecting circles4910 and 4920. Circle 4910 represents the curvature of the cornea 104 ofeye 100. Although the cornea 104 of eye 100 is slightly flatter at itsperiphery that at its center, the cornea 104 will be assumed to bespherical. This assumption does not significantly affect the accuracy ofthe calculations for determining the position for scleral pocket 120.The radius of circle 4910 is designated with the letter C.

Circle 4920 represents the curvature of the sclera 102 of eye 100. Theradius of circle 4920 is designated with the letter D. The center ofcircle 4920 represents the center of a scleral shell 102 that representsthe sclera 102 of eye 100. The circumference of circle 4910 and thecircumference of circle 4920 intersect at point 4930 and point 4940. Itis understood that FIG. 1 represents a cross section of eye 100 and thatpoint 4930 and point 4940 are only two of the points on the cornealdiameter of eye 100. The plane 4950 that is perpendicular to the axis ofeye 100 and that passes through point 4930 and point 4940 on the cornealdiameter is referred to as the corneal plane 4950.

The diameter of the cornea 104 is designated with the letter A. Thedistance from the anterior central corneal surface to the corneal plane4950 is designated with the letter E. The distance from the cornealplane 4950 to the center of circle 4920 (i.e., the center of the scleralshell 102) is designated with the letter F. The axial length of eye 100is designated with the letter B. As shown in FIG. 1, the axial length Bis equal to the sum of the distances D, F and E.

The method of the present invention first determines the value of radiusD of circle 4920 from values that can be empirically measured. Thevalues of the corneal diameter A, the mean radius of curvature C of thecornea, and the axial length B of the eye 100 can be measured.Specifically, an ultrasound biomicroscope may suitably be used todetermine a value for the corneal diameter A. Mean central keratometrymay be used to determine a value for the mean radius of curvature C ofthe cornea. An ultrasound biomicroscope or an A-scan may be used todetermine a value of the axial length B of eye 100. Of course, thoseskilled in the art will understand that alternate approaches may be usedin lieu of any of the same.

A measured value of corneal diameter A may be twelve millimeters (12.00mm). A measured value for the radius of curvature C of the cornea may beeight millimeters (8.00 mm). A measured value for the axial length B maybe twenty-two and three tenths millimeters (22.3 mm). A value of theradius D of the scleral shell may be calculated from these values.

From the geometry of eye 100 shown in FIG. 1, the axial length B isequal to the sum of the distances D, F and E. The value of the distanceE can be determined from the values of A and C by using the Pythagoreantheorem:

$\begin{matrix}{E = {C - \left\lbrack {C^{2} - \left( {A/2} \right)^{2}} \right\rbrack^{\frac{1}{2}}}} & (1)\end{matrix}$

The value of the distance F can be determined from the values of A and Dby using the Pythagorean theorem:

$\begin{matrix}{F = \left\lbrack {D^{2} - \left( {A/2} \right)^{2}} \right\rbrack^{\frac{1}{2}\;}} & (2)\end{matrix}$

The value of D can then be determined by using the fact that the axiallength B is equal to the sum of the distances D, F and E.

$\begin{matrix}{B = {D + \left\lbrack {D^{2} - \left( {A/2} \right)^{2}} \right\rbrack^{\frac{1}{2}} + C - \left\lbrack {C^{2} - \left( {A/2} \right)^{2}} \right\rbrack^{\frac{1}{2}}}} & (3)\end{matrix}$

Inserting the measured values for A, B and C into Equation (3) andsolving for D gives a value for D of ten and seven tenths millimeters(10.7 mm).

Now consider the structures of eye 100 shown in FIG. 2. From empiricalmeasurements it is known that the distance from the anterior centralcorneal surface to the anterior surface of the lens 108 is three andseven tenths millimeters (3.7 mm). This distance is designated with theletter G. It is also known from empirical measurements that the distancefrom the anterior central corneal surface to the posterior surface ofthe lens 108 is seven and seven tenths millimeters (7.7 mm). Thethickness of the lens 108 is the difference of these two distances. Thethickness of the lens 108 is given by 7.7 mm minus 3.7 mm. The thicknessof the lens 108 is four millimeters (4.0 mm). The thickness of the lens108 is designated with the letter J. Symbolically, the thickness J oflens 108 equals H-G.

It is known that the position of the lens equatorial plane 130 (withrespect to the anterior surface of the lens 108) can be determined bymultiplying the thickness of the lens 108 by an empirical percentagethat has been previously determined from measurements made on therelative position of the lens equator of cadaver eyes. Assume that thepresent measurement is being made for an eye 100 of a fifty year oldperson. From empirical measurements the appropriate percentage is fortypercent (40%). The position of the lens equatorial plane 130 is fortypercent (40%) of four millimeters (4.0 mm) (i.e., one and six tenthsmillimeters (1.6 mm)) from the anterior surface of the lens 108.

This means that the distance from the anterior central corneal surfaceto the lens equatorial plane 130 is given by the sum of the distance Gand the distance 1.6 mm. As previously noted, the value of G is 3.7 mm.Therefore, the distance from the anterior central corneal surface to thelens equatorial plane 130 is five and three tenths millimeters (5.3 mm).

From FIG. 49 it is known that the distance E from the anterior centralcorneal surface to the corneal plane 4950 is given by Equation (1).Inserting the measured values for A and C into Equation (1) and solvingfor E gives a value for E of two and seven tenths millimeters (2.7 mm).

The distance between the corneal plane 4950 and the lens equatorialplane 130 is designated by the letter L. The distance L may be obtainedby subtracting the distance from the anterior central corneal surface tothe corneal plane 4950 (i.e., the distance E) from the distance from theanterior central corneal surface to the lens equatorial plane 130. Thedistance L equals 5.3 mm minus 2.7 mm. That is, the distance L equalstwo and six tenths millimeters (2.6 mm).

From FIG. 49 it is also known that the distance F from the center of thescleral shell 102 to the corneal plane 4950 is given by Equation (2).Inserting the measured value for A and the calculated value for D intoEquation (2) and solving for F gives a value for F of eight and eightysix hundredths millimeters (8.86 mm).

The distance from the center of the scleral shell 102 to the lensequatorial plane 130 is designated by the letter K. The distance K maybe obtained by subtracting the distance between the corneal plane 4950and the lens equatorial plane 130 (i.e., the distance L) from thedistance from the center of the scleral shell 102 to the corneal plane4950. The distance K equals 8.86 mm minus 2.6 mm. That is, the distanceK equals six and twenty six hundredths millimeters (6.26 mm).

The distance from the axis of eye 100 to the point where the lensequatorial plane 130 crosses the sclera 102 is designated by the letterM. The value of the distance M can be determined from the values of Dand K by using the Pythagorean theorem:

$\begin{matrix}{M = \left\lbrack {D^{2} - K^{2}} \right\rbrack^{\frac{1}{2}}} & (4)\end{matrix}$

Inserting the value of 10.7 mm for D and the value of 6.26 mm for K intoEquation (4) and solving for M gives a value for M of eight and sixtyseven hundredths millimeters (8.67 mm).

The front of the scleral pocket 120 should be placed four hundred fiftymicrons (450μ) posterior to the lens equatorial plane 130. Four hundredfifty microns is equivalent to four hundred fifty thousandths of amillimeter (0.450 mm). The point of location for the front of thescleral pocket 120 is designated with the letter Q in FIG. 50.

The distance from the center of the cornea 104 to the point of locationfor the front of the scleral pocket 120 is designated with the letter N.The distance N is equal to the sum of the distance M and four hundredfifty thousandths of a millimeter (0.450 mm). The distance N equals 8.67mm plus 0.450 mm. That is, the distance N equals nine and twelvehundredths millimeters (9.12 mm).

The radius of the scleral tissue fixation tool 3000 is seven hundredfifty microns (750μ). Seven hundred fifty microns is equivalent to sevenhundred fifty thousandths of a millimeter (0.750 mm). The distance fromthe base plate 1730 of the surgical tool hand piece to the anterior edgeof the drive blade 1140 is seven hundred fifty microns (750 a).

The position to place the center of the scleral tissue fixation tool3000 is designated with the letter P in FIG. 50. In order to determinethe position P subtract a distance of one and one half millimeters (1.5mm) from the distance N. The distance P is the distance from the axis ofeye 100 to the center of the scleral tissue fixation tool 3000. Thedistance P equals 9.12 mm minus 1.5 mm. That is, the distance P equalsseven and sixty two hundredths millimeters (7.62 mm). As will be morefully described, an applanation marking plate may be used to mark theposition of the center of the scleral tissue fixation tool 3000 on thesclera of eye 100. A micrometer is used to set the value of 7.62 mm onthe applanation marking plate.

FIG. 51 illustrates an applanation marking plate assembly 5100.Applanation marking plate assembly 5100 comprises applanation markingplate 5110. Applanation marking plate 5110 is a transparent plate madeof clear glass, plastic or other suitable material. In one advantageousembodiment, applanation marking plate 5110 comprises a square havingsides that are approximately sixteen millimeters (16 mm) in length.

Applanation marking plate assembly 5100 further comprises a circularmarking ring 5120 on applanation marking plate 5110. Marking ring 5120has a circular shape with the center of the circle located in the centerof applanation marking plate 5110. The size of marking ring 5120 isadjustable. Applanation marking plate assembly 5100 comprises amicrometer 5140 for adjusting the size of marking ring 5120.

Applanation marking plate assembly 5100 further comprises an applanatingcircle 5130 on applanation marking plate 5110. The center of applanatingcircle 5130 is located in the center of applanation marking plate 5110.The size of applanating circle 5130 is fixed. In one advantageousembodiment, the diameter of applanating circle 5130 is three millimeters(3.0 mm). The diameter of applanating circle 5130 may be greater thanthree millimeters (3.0 mm) or less than three millimeters (3.0 mm).

Applanation marking plate assembly 5100 may be used to mark the positionfor placing the scleral tissue fixation tool 3000 on the sclera of eye100. First the surgeon uses micrometer 5140 to adjust the size ofmarking ring 5120 so that the radius of marking ring 5120 is equal toseven and sixty two hundredths millimeters (7.62 mm). Then the surgeonplaces the applanation marking plate 5110 on the center of the cornea ofeye 100.

To determine the center of the cornea 104 of eye 100 the surgeon may useany of a number of prior art techniques. An exemplary prior art systemfor making corneal measurements is disclosed in U.S. Pat. No. 6,520,958entitled “System and Methods for Imaging Corneal Profiles” issued Feb.18, 2003.

To determine the center of the cornea 104 of eye 100 the surgeon may usea central fixation light source (not shown). The fixation light from thecentral fixation light source enters through one of the side ports of asurgical microscope (not shown). The fixation light then exits throughan objective lens on the same side of the surgical microscope. Assumethat the fixation light enters through the right side port and exitsthrough the right objective lens of the surgical microscope.

The patient fixates the fixation light that comes through the rightobjective lens of the surgical microscope while the surgeon looksthrough only the right eyepiece of the surgical microscope. The surgeonthen aligns the center of applanating circle 5030 with the patient'scorneal Purkinje image of the fixation light to determine the locationof the center of the cornea 104 of the patient.

The surgeon then applanates the cornea 104 of eye 100 to insure that theapplanation of the cornea 104 of eye 100 is circular. The surgeon mustmake sure that the measurement is being made from the center of thecornea 104 and that the applanation is circular. The surgeon pressesapplanation plate 5110 down on the cornea 104 of eye 100 and marks acircle (on individual points) on the sclera 102 of eye 100 at thelocation of marking ring 5120. The marks on the sclera 102 of eye 100define the position for locating the center of the scleral tissuefixation tool 3000. This location marks an optimum position for placingscleral pocket 120 to receive scleral prosthesis 200.

FIG. 52 illustrates a controller 5210 that is capable of carrying outthe method of the present invention. Controller 5210 is coupled to andreceives eye measurements from eye measurement equipment 5220. Eyemeasurement equipment 5220 may comprise, for example, an ultrasoundbiomicroscope for determining a value for the corneal diameter A, akeratometer for determining a value for the mean radius of curvature Cof the cornea, and an ultrasound biomicroscope for determining a valueof the axial length B of eye 100.

Controller 5210 is also coupled to an input unit 5230. Controller 5210can receive input parameters and other information from the surgeonthrough input unit 5230, a memory, or other device or processor. Forexample, the surgeon can use input unit 5230 to inform controller 5210of the age of the person whose eye is being measured.

Controller 5210 comprises a software processor 5240 that is capable ofexecuting computer instructions stored in a memory (not shown) withincontroller 5210. Software processor 5240 comprises an operating system5250 and an eye model application 5260. Eye model application 5260comprises computer software instructions for making the variouscalculations of the method of the present invention.

Eye model application 5260 receives the values of the measuredparameters of eye 100 that are measured by eye measurement equipment5220. Eye model application 5260 uses the eye measurement values fromeye measurement equipment 5220 and input from input unit 5230 tomathematically model the operation of eye 100 in accordance with thesteps of the method of the present invention. Eye model application 5260contains a database (not shown) that contains the empirically determinedpercentages (as a function of the age of eye 100) with which to multiplythe thickness of lens 108 to determine the position of lens equatorialplane 130.

Eye model application 5260 obtains information about eye 100 from themathematical model of eye 100 that is created by eye model application5260. In particular, eye model application 5260 calculates a preciselocation for a scleral pocket 120 on the sclera 102 of eye 100.Information from eye model application 5260 may be output by controller5210 to a data display 5270 for the surgeon to review.

Information from eye model application 5260 may also be supplied tosurgical tool controller 1200 to assist the surgical tool controller inaccurately positioning blade 1140 of surgical tool 1100. Surgical toolcontroller 1200 may use information from eye model application 5260 toautomatically determine an incision point for the incision to createscleral pocket 120 while surgical tool 1100 is in place over the sclera102 of eye 100. As previously mentioned, in one advantageous embodiment,scleral prosthesis 200 is capable of being filled with a fluid. Surgicaltool controller 1200 may use information from eye model application 5260to select a size of scleral prosthesis 200 when scleral prosthesis 200is filled with fluid after scleral prosthesis 200 has been placed withinscleral pocket 120.

Information from eye model application 5260 may also be supplied toapplanation marking plate assembly 5100 to operate micrometer 5140 toaccurately position marking ring 5120.

FIG. 53 illustrates a flow chart showing an advantageous embodiment ofthe method of the present invention. The steps of the method arecollectively referred to with reference numeral 5300.

The values of the corneal diameter A, the corneal radius of curvature C,and the axial length B of eye 100 are measured (step 5310). The value ofthe radius D of the scleral shell 102 is then calculated from themeasured values of A, B, and C. (step 5320). The thickness J of the lensis calculated and the position of the lens equatorial plane 130 iscalculated (step 5330).

The distance L between the corneal plane 4950 and the lens equatorialplane 130 is then calculated (step 5340). The distance K from the centerof the scleral shell 102 to the lens equatorial plane 130 is thencalculated (step 5350). The distance M from the axis of eye 100 to thepoint where the lens equatorial plane 130 crosses the sclera 102 is thencalculated (step 5360). The distance N from the center of cornea 104 tothe front of the scleral pocket 120 is then calculated (step 5370). Themethod of present invention precisely determines the optimum positionfor the location of scleral pocket 120.

The invention having now been fully described, it should be understoodthat it may be embodied in other specific forms or variations withoutdeparting from its spirit or essential characteristics. Accordingly, theembodiments described above are to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than the foregoing description,and all changes which come within the meaning and range of equivalencyof the claims are intended to be embraced therein.

1. For use with a surgical tool for making an incision in scleral tissueof an eye for forming a scleral pocket within the scleral tissue of theeye to receive a scleral prosthesis, an apparatus for locating aposition on the sclera of the eye to form said scleral pocket, saidapparatus comprising: a controller that is operable to: (i) receive eyemeasurements that measure a size of portions of said eye, wherein saidcontroller comprises a software processor; and (ii) use said eyemeasurements to create a mathematical model of said eye; and (iii)determine from said mathematical model of said eye a location on saidsclera of said eye for making an incision having the form of a scleralpocket that is capable of receiving said scleral prosthesis.
 2. Anapparatus as claimed in claim 1 wherein said controller is capable ofdetermining from said mathematical model of said eye a location on thesclera of said eye where a projection of a lens equatorial plane of saideye intersects with the sclera of said eye.
 3. An apparatus as claimedin claim 1 wherein said controller is capable of determining from saidmathematical model of said eye a radius D of a scleral shell of said eyefrom a measured value of corneal diameter A of said eye, a measuredvalue of mean radius of curvature C of said eye, and a measured value ofan axial length B of said eye.
 4. An apparatus as claimed in claim 2wherein said controller is capable of determining from said mathematicalmodel of said eye a location of said lens equatorial plane with respectto the anterior surface of a lens of said eye.
 5. An apparatus asclaimed in claim 4 wherein said controller is capable of determiningfrom said mathematical model of said eye said location of said lensequatorial plane by multiplying a thickness of said lens by an empiricalpercentage stored within said controller.
 6. An apparatus as claimed inclaim 5 wherein said controller is capable of determining from saidmathematical model of said eye a distance between a corneal plane ofsaid eye and said lens equatorial plane of said eye.
 7. An apparatus asclaimed in claim 6 wherein said controller is capable of determiningfrom said mathematical model of said eye a distance K from a center ofsaid scleral shell of said eye to said lens equatorial plane.
 8. Anapparatus as claimed in claim 7 wherein said controller is capable ofdetermining from said mathematical model of said eye a distance M froman axis of said eye to a point on said sclera of said eye where aprojection of said lens equatorial plane of said eye intersects with thesclera of said eye.
 9. An apparatus as claimed in claim 8 wherein saidcontroller is capable of determining from said mathematical model ofsaid eye a distance N from the center of a cornea of said eye to aposition Q where it is optimal to locate a front of said scleral pocketon said sclera of said eye.
 10. An apparatus as claimed in claim 9wherein said controller is capable of determining from said mathematicalmodel of said eye a distance from the center of said cornea of said eyeto a position P on the sclera of said eye where it is optimal to place acenter of a scleral tissue fixation tool to restrain the movement ofsaid surgical tool when said surgical tool makes an incision in saidsclera of said eye to form said scleral pocket.
 11. An apparatus asclaimed in claim 1 wherein said controller is capable of receivinginformation concerning said eye from an input unit.
 12. An apparatus asclaimed in claim 1 wherein said controller is further capable ofproviding information derived from said mathematical model of said eyeto one of: a data display, a surgical tool controller, and anapplanation marking plate assembly.
 13. For use with a surgical tool formaking an incision in scleral tissue of an eye for forming a scleralpocket within the scleral tissue of the eye to receive a scleralprosthesis, a method for locating a position on the sclera of the eye toform said scleral pocket, said method comprising the steps of: receivingeye measurements that measure a size of portions of said eye within acontroller that comprises a software processor; using said eyemeasurements within 111 said controller to create a mathematical modelof said eye; and determining from said mathematical model of said eye alocation on said sclera of said eye for making an incision having theform of a scleral pocket that is capable of receiving said scleralprosthesis.
 14. A method as claimed in claim 13 further comprising thestep of: determining from said mathematical model of said eye a locationon the sclera of said eye where a projection of a lens equatorial planeof said eye intersects with the sclera of said eye. 15.-19. (canceled)20. A method as claimed in claim 13 further comprising the steps of:receiving in said controller from an input unit, information concerningsaid eye; and providing information derived from said mathematical modelof said eye to at least one of: a data display, a surgical toolcontroller, and an applanation marking plate assembly.
 21. The apparatusof claim 1, wherein the location of the scleral pocket on the sclera isdetermined such that the scleral prosthesis, once inserted into thescleral pocket, increases an effective working distance of a ciliarymuscle in the eye to increases an amplitude of accommodation of the eye.